Method of telegraphing by the use of alternating current



Sept. 3, i925.

. .2. P. FERRE ER ET AL METHOD OF TELEGRAPHING BY THE USE OF ALTERNATING CURRENT Filed A112,. 29 1923 2 Sheets-Sheet 1 Sept 1, W25.

4. P; FERRH'ER ET AIL. METHOD OF TELEGRAPHING BY THE USE OF ALTERNATING CURRENT 2 Sheets-Sheet 2 Filed Aug. 29. 1925 Patented Sept. 1, 1925.

1,551,316 PATENT OFFICE.

JOHN P. FERRITER, OF OCEANIORT, AND WRIGHT H. JOHNSON, OF RED BANK, NEW JERSEY.

METHOD OF TELEGRAPHING BY THE USE OF ALTEBNATING CURRENT.

Application filed August 28, 1928. Serial N'o. 660,025.

To all wkomit may cancer-%.;

Be it known that we, JOHN P. FERRITER and WRIGHT H. JoHNsoN, citizens of the United States, residing, respectively, at Oceanport and Red Bank, in the county of Monmouth and State of New Jersey, have invented certain new and useful Improvements in hlethods of Telegraphing by the as one of its Use of Alternating Current, of whichthe following is a specification.

This invention relates to alternating current telegraph systems and has for one of' its objects the adaptation to duplex work- It is well known for example that high frequency carrierwave currents have been employed for signalling. Moreover that several signallin'gcurren'ts of different frequencies have been simultaneously transmitted and received by means of wave filters. However, great difiiculty has been experienced by virtue of the frequencies being of high degree introducing strong attenuation efl'ects. Since the frequencies employed by the present system are very low, ordinary telegraph lines are made suitable for this type of transmission and especially in connection with vacuum tube repeater 4 systems, since it is known that mechanical repeaters are much less eflicient than those of the-vacuum tube type. a

By means of the present invention which principal features involves the of thoroughly synchronized and propi affected without distorting "far i on one hand, and the amplified half wave chronized transmitter that in order to ma e erly modulated half-wave modifiers, it is possible to operate printers over submarine cables when 'due to attenuation signals would beflimpossible by ordinary known means. Moreover, the signals suffer a minidistributor is connected to a separate autothe amplitudes are graduatedly the final sinoidal mum of distortion as only of "the sinoidal half-waves shape ofthe waves.

In order to more clearly grasp the scope of this invention the following figures are made part of the specifications and r Fig. 1, is a diagrammatic representation the unmodified alternating current wave intensities for signalling and E by way of example.

Fig. 2 schematically represents the synmeans employed. referring to Figure '1, the system completely the letters A, .11,

It will be seen b effective,

rent generator directly.

. distributor brush it is necessary tostart intensifying a selected half cycle at its beginning or at the zero point, and to complete the intensification at the end of the half cycle. To accomplish this end it is requisite that synchronism be maintained between the alternating current and the transmitted signals. Our method of maintaining this synchronism is as follows.

We connect a small alternating current generator thru gears to the shaft of the printer distributor in such a manner that the distributor drives the alternating cur- This alternating current generator is caused to furnish current to the telegraph line continuously and, as the generator is driven by the distributor, which transmits the telegraph signals, they are automatically kept in phase regardless of any variation in the speed of the distributor.

Our method of varying the intensity of the half cycles is as follows. We modify the telegraph duplex on which system operates so that, instead of transmitting marking and spacing signals by alternating the polarity of the applied E. M. F., it transmits marking signals by applying the total E. M. F. the line and transmits spacing signals by applying a reduced E. M. Fnto the line. This is accomplished as shown in Figure 2. p In Figure 2, (D) is the distributor on which five transmitting segments are shown. The brush arm, which is rotating continuously, is connected directly to the line and.

matic tape transmitter, one of which is represented by K). The position of the. armature of (K determines the valueof the E. M. F. applied to the line and, as the passes over the segment to which (K) isconnected, this E. M. F. will cause current to flow. It will be remembered that'the generator (G) which is geared to (D) and rotating in synchronism with it is generating alternating current at all times and that, when the distributor brush first touches any transmitting segment, the alternating current is at the zero point and, as the brush passes over the segment, the current gradually increases until to the line at point the brush reaches the middle of the segment and thereafter the current decreases until it reaches the zero point again just as the brush leaves the segment. This operation is repeated on the following segment with (S), thru point (X), and to the midpointof transformer (T) where it divides between the line and the artificial line as is usual in duplexes. In following this path, the current passed thru a resistance of 100 ohms before reaching point (X). During this time, a maximum E. M. F. was applied (X) and a marking signal was transmitted. With the key closed at (O), the current would flow from generator (G) thru resistance (B) and resistance (A) to (X), where the parallel paths are provided, one from (X) thru brush arm (BR), segment (S), contact (0) and resistance (L) to the earth; the other from point (X) to the midpoint of transformer (T), where it divides between the line and the artificial line. It will be seen that, in this position of the path from (X) to earth thru (L) serves as voltage divider and that the potential 'drop thru this path will be the same as the drop thru the line or thru the artificial line and, as (L) can be made smaller than (B) and (A) in series, the result will be a lower potential applied to the line at (X) than was the case when (K) was closed at (C).

Any desired proportion of current passing over the line may be obtained by choosing the proper values of (B), (A) and (L). In doing thispcare must be taken not to choose the resistances so that the joint resistance to an incoming current from point (X) to the earth will be difi'erent when (K) is closed at (C) from the joint resistance when (K) is closed at (0); otherwise the balance of thedistant duplex will be changed at each change of the position of j 7.

, To insure the same joint resistance in either position of (K) and to provide the desired drop of potential at the following formulas may be used..

B2 rn e the duplex receiver preferably involves a vacuum tube system direct current for rectifying both halves of the alternating current waves received over the line. However, any other type of suitable receiver can be employed.

Having thus described our invention, we claim:

A system of signalling by means of alternating currents comprising a distributor means for allocating groups of half-Waves in sequence for characterizing a signal element, a line and an artificial line, a transformer, a pair of vacuum tube detectors having their grids in series through the secondary of said transformer, keying means in said artificial line comprising a series of resistances for modifying the half-wrve componentsof the groups to give a distinguishing characteristic to each signal element, and an alternating current means for supplying the requisite half-wave groups to said distribu tor means, to maintain the normal phase relationship with respect to the alternating current wave train a whole.

In testimony whereof we aflix our signatures. a a

JOHN PQ'FERRITER. a WRIGHT 1-1., JOHNSON. 

